[SCSI] NCR5380: Fix bugs and canonicalize irq handler usage

* Always pass the same value to free_irq() that we pass to
  request_irq().  This fixes several bugs.

* Always call NCR5380_intr() with 'irq' and 'dev_id' arguments.

  Note, scsi_falcon_intr() is the only case now where dev_id is not the
  scsi_host.

* Always pass Scsi_Host to request_irq().  For most cases, the drivers
  already did so, and I merely neated the source code line.  In other
  cases, either NULL or a non-sensical value was passed, verified to be
  unused, then changed to be Scsi_Host in anticipation of the future.

In addition to the bugs fixes, this change makes the interface usage
consistent, which in turn enables the possibility of directly
referencing Scsi_Host from all NCR5380_intr() invocations.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/sun3_scsi_vme.c

@@ -230,7 +230,7 @@ static int sun3scsi_detect(struct scsi_host_template * tpnt)
         ((struct NCR5380_hostdata *)instance->hostdata)->ctrl = 0;
 
 	if (request_irq(instance->irq, scsi_sun3_intr,
-			     0, "Sun3SCSI-5380VME", NULL)) {
+			0, "Sun3SCSI-5380VME", instance)) {
 #ifndef REAL_DMA
 		printk("scsi%d: IRQ%d not free, interrupts disabled\n",
 		       instance->host_no, instance->irq);
@@ -279,7 +279,7 @@ static int sun3scsi_detect(struct scsi_host_template * tpnt)
 int sun3scsi_release (struct Scsi_Host *shpnt)
 {
 	if (shpnt->irq != SCSI_IRQ_NONE)
-		free_irq (shpnt->irq, NULL);
+		free_irq(shpnt->irq, shpnt);
 
 	iounmap((void *)sun3_scsi_regp);